In the process of bonding die, such as flip chips, to a microelectronic substrate to form a microelectronic package, the use of thermal compression bonding followed by post-curing is known. Flip chips are surface-mounted chips having connecting metal lines attached to pads or bumps on the underside of the chips. A chip or die is typically mounted on an IC substrate to form an IC assembly. For example, a die may be mounted on a package substrate and the resulting package mounted on a printed circuit board (“PCB”). A die may also be directly mounted to a PCB. Underfill is provided between the die and the IC substrate to support the electrical connections, to protect them from the environment, and to reduce the thermomechanical stresses on the die connection. Such thermomechanical stresses are typically caused by the high temperatures necessary to reflow bumps on the die and/or on the substrate together to form the electrical connections, or joints. During cooling, different shrinkage amounts of the die and substrate could lead to cracks within the die, especially when the die uses a mechanically weak interlayer dielectric (ILD). Such stresses could lead to increased under-bump ILD cracking. As a result of formation of the joints, the underfill material is partially cured, and can withstand some of the stresses mentioned above. After joint formation, the partially cured underfill is again typically cured at elevated temperatures in a cure oven. The cured underfill is adapted to at least partially compensate for stresses caused in the package by differing coefficients of thermal expansion (CTE's) of the die on the one hand and of the substrate on the other hand. However, after joint formation but before further curing of the partially cured underfill material, differing shrinkage rates of the die and the substrate could still cause damage to the device during a transfer of the bonded die and substrate to the cure oven.
A conventional method of mitigating the above problem is to reduce a transfer time of the bonded die and substrate from the formation site of the joints to the curing site of the underfill material, such as, for example, by minimizing a transfer distance of the same. However, the above method disadvantageously fails to fully address the following: the carrier acting as a heat sink and thus cooling the substrate very quickly after joint formation; the possibility of newly developed underfill materials or newly developed, more delicate ILD materials that may not perform adequately as the conventional levels of temperature control; a reliance on ambient temperature and humidity conditions that may not be suitable for all factory environments.
A method of bonding a die to a substrate and an arrangement for carrying out the method are needed that address the disadvantages of the prior art.